''Thuridilla moebii'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

sacoglossa Sacoglossa, commonly known as the sacoglossans or the "solar-powered sea slugs", are a superorder of small sea slugs and sea snails, marine gastropod mollusks that belong to the clade Heterobranchia. Sacoglossans live by ingesting the cellular co ...

sea slug Sea slug is a common name for some marine invertebrates with varying levels of resemblance to terrestrial slugs. Most creatures known as sea slugs are gastropods, i.e. they are sea snails (marine gastropod mollusks) that over evolutionary time ...

, a shell-less marine opisthobranch gastropod mollusc in the family

Plakobranchidae Plakobranchidae is a family of sea slugs, marine opisthobranch gastropod mollusks in the superfamily Plakobranchoidea. They superficially resemble nudibranchs but they are sacoglossans, members of the clade Sacoglossa within the Opisthobranchia ...

. It is found in shallow water in the tropical west and central Indo-Pacific region.

Description

''Thuridilla moebii'' is a small, slender slug, growing to a maximum length of about . On either side of the body there are

parapodia In invertebrates, the term parapodium ( Gr. ''para'', beyond or beside + ''podia'', feet; plural: parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in annelids, where they are paired, unjointed ...

which fold up and over the back, joining at the top, and forming a sheath from which the head projects at the front. The basic colour is translucent white, often tinted with bluish-green, or even pale blue. Along the upper surface is a bold longitudinal, zigzag band of contrasting colour, usually deep orange above and blackish below (but sometimes all black), uniformly speckled with white dots. The head is white and bears a pair of large, rolled

rhinophore A rhinophore is one of a pair of chemosensory club-shaped, rod-shaped or ear-like structures which are the most prominent part of the external head anatomy in sea slugs, marine gastropod opisthobranch mollusks such as the nudibranchs, sea ha ...

s, which extend forward, the tips of which match the colouring of the band on the body. The front edge of the foot has a similar colouring.

Distribution and habitat

''Thuridilla moebii'' is found in shallow water in the tropical and subtropical Indo-Pacific region, its range extending from South Africa to Western Australia, including

Mayotte Mayotte (; french: Mayotte, ; Shimaore: ''Maore'', ; Kibushi: ''Maori'', ), officially the Department of Mayotte (french: Département de Mayotte), is an overseas department and region and single territorial collectivity of France. It is loca ...

, the

Comoro Islands The Comoro Islands or Comoros (Shikomori ''Komori''; ar, جزر القمر , ''Juzur al-qamar''; french: Les Comores) form an archipelago of volcanic islands situated off the southeastern coast of Africa, to the east of Mozambique and northwes ...

, Réunion and

Mauritius Mauritius ( ; french: Maurice, link=no ; mfe, label= Mauritian Creole, Moris ), officially the Republic of Mauritius, is an island nation in the Indian Ocean about off the southeast coast of the African continent, east of Madagascar. It ...

. Its habitat includes sandy areas where detritus accumulates, and rocky reefs with scanty coral cover and suitable algal growth.

Ecology

Members of the '' Thuridilla'' genus are vegetarians, feeding on algae. ''Thuridilla moebii'' has a saw-edged radula which it uses to grate or puncture the cell walls of the algae on which it feeds. The individual sea slug examined when the species was redescribed in 1995 had 23 triangular teeth in a single row on the radula. The teeth are constantly being replaced as they wear down, the discarded teeth falling into a special sac in the mouth where they are retained. The precise diet for this species is not known, but in Réunion it is reported to often be seen on a green alga, the spherical turtle shell ('' Bornetella sphaerica''). ''Thuridilla moebii'' is a simultaneous hermaphrodite; the penis is located on the head just behind the right rhinophore. When breeding, two individuals entwine in such a way as to bring the right sides of their heads together, and sperm is passed between the pair. Later, each individual lays an orange egg ribbon in the form of a wide spiral, sticking the gelatinous thread to the substrate.

References

{{Taxonbar, from=Q14491679 Plakobranchidae Gastropods described in 1888